Antifungal activities of silver and selenium nanoparticles stabilized with different surface coating agents

BACKGROUND

Extensive and growing use of different chemical pesticides that affect both the environment and human health raises a need for new and more suitable methods to deal with plant pathogens. Nanotechnology has enabled the use of materials at the nanoscale with exceptional functionality in different economic domains including agricultural production. This study aimed to evaluate antifungal potential of selenium nanoparticles (SeNPs) and silver nanoparticles (AgNPs) stabilized with different surface coatings and characterized by different surface charge on plant pathogenic fungi Macrophomina phaseolina, Sclerotinia sclerotiorum and Diaporthe longicolla.

RESULTS

AgNPs were coated with three different stabilizing agents: mono citrate (MC-AgNPs), cetyltrimethyl ammonium bromide (CTAB-AgNPs) and polyvinylpyrrolidon (PVP-AgNPs). SeNPs were coated with poly-l-lysine (PLL-SeNPs), polyacrylic acid (PAA-SeNPs), and polyvinylpyrrolidon (PVP-SeNPs). Seven different concentrations (0.1, 0.5, 1, 5, 10, 50 and 100 mg L^-1 ) of nanoparticles were applied. All AgNPs and SeNPs significantly inhibited the growth of the tested fungi. Among the tested NPs, PVP-AgNPs showed the best inhibitory effect on the tested plant pathogenic fungi, especially against S. sclerotiorum. The similar inhibition of the sclerotia formation was observed for S. sclerotiorum treated with PLL-SeNPs.

CONCLUSION

Obtained results provides new insights on fungicide effect of AgNPs and SeNPs stabilized with different coating agents on different plant pathogens. Further work should focus on detailed risk/benefit ratio assessment of using SeNPs or AgNPs in agriculture taking into account whole agroecosystem. © 2020 Society of Chemical Industry.

Effect of Edible Coating on Antioxidants and Certain Properties of Dried Jerusalem Artichoke

BACKGROUND AND OBJECTIVE

Most food industries try to solve the problem of dried food quality by using optimum pre-treatments before subjecting to hot air drying. The edible coating is considerably extended shelf-life of dried foods. The objectives of this research were to investigate the effect of edible coating agents (modified cassava starch and sodium caseinate) on properties of dried Jerusalem artichoke (JA) slices.

MATERIALS AND METHODS

Pieces of the sample were coated by dipping in the coating solution for 10 min both for atmospheric coating (AC) and vacuum coating (VC). The weight ratio of the sample to the solution was 1:2. The VC was conducted in a closed desiccator connected to a vacuum pump with a residual pressure of 150 m bar controlled during 10 min of dipping.

RESULTS

The coating agents resulted in improvements in product qualities. Browning and shrinkage were reduced significantly (p<0.05). The antioxidant properties were similar between a hot air-dried product and a freeze-dried product. There was no observed benefit of using vacuum pressure rather than atmospheric pressure. Sensory acceptance of coated products was similar to that of an uncoated product.

CONCLUSION

The edible coating with modified cassava starch or sodium caseinate was, therefore, an efficient pre-treatment and could be applied with conventional drying to produce healthy fruit and vegetable snacks by using a simple and inexpensive method.

Synthesis and Application of a Cationic Polyamine as Yankee Dryer Coating Agent for the Tissue Paper-Making Process

Tissue paper is of high importance worldwide and, continuously, research is focused on improvements of the softening and durability properties of the paper which depend specifically on the production process. Polyamide-amine-epichlorohydrin (PAE) resins along with release agents are widely used to adhere the paper to the yankee dryer (creping cylinder) in paper manufacture. Nevertheless, these resins are highly cationic and they normally adhere in excess to the paper which negatively affects the creping process and the quality of the paper. For this reason, a low cationic polyamine-epichlorohydrin coating (Polycoat 38®) was synthesized from a diamine supplied by Disproquin S.A.S. and epichlorohydrin. The analysis of the synthesized polymer was carried out by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H-NMR). The molecular weight of the polymer was obtained by gel permeation chromatography (GPC), physical-chemical properties such as kinematic viscosity, percentage of solids, density, charge density were measured and compared with a commercial PAE resin (Dispro620®) Thermal stability of the Polycoat 38® and glass transition temperature in presence of a release agent (Disprosol 17®) were also evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Finally, a peel adhesion test and an absorption durability assessment were carried out together with the evaluation of the creeping efficiency of the paper by caliber and tensile measurements in a tissue (towel paper) production plant, demonstrating a superior performance in the paper creping process as compared to some commercially available products.

Dissolution of Silver Nanoparticles in Colloidal Consumer Products: Effects of Particle Size and Capping Agent

The utilization of silver nanoparticles (AgNPs) in consumer products has significantly increased in recent years, primarily due to their antimicrobial properties. Increased use of AgNPs has raised ecological concerns. Once released into an aquatic environment, AgNPs may undergo oxidative dissolution leading to the generation of toxic Ag+. Therefore, it is critical to investigate the ecotoxicological potential of AgNPs and determine the physicochemical parameters that control their dissolution in aquatic environments. We have investigated the dissolution trends of aqueous colloidal AgNPs in five products, marketed as dietary supplements and surface sanitizers. The dissolution trends of AgNPs in studied products were compared to the dissolution trends of AgNPs in well-characterized laboratory-synthesized nanomaterials: citrate-coated AgNPs, polyvinylpyrrolidone-coated AgNPs, and branched polyethyleneimine-coated AgNPs. The characterization of the studied AgNPs included: particle size, anion content, metal content, silver speciation, and capping agent identification. There were small differences in the dissolved masses of Ag+ between products, but we did not observe any significant differences in the dissolution trends obtained for deionized water and tap water. The decrease of the dissolved mass of Ag+ in tap water could be due to the reaction between Ag+ and Cl-, forming AgCl and affecting their dissolution. We observed a rapid initial Ag+ release and particle size decrease for all AgNP suspensions due to the desorption of Ag+ from the nanoparticles surfaces. The observed differences in dissolution trends between AgNPs in products and laboratory-synthesized AgNPs could be caused by variances in capping agent, particle size, and total AgNP surface area in suspensions.

Influence of Oilseed Rape Seed Treatment with Imidacloprid on Survival, Feeding Behavior, and Detoxifying Enzymes of Mustard Aphid, Lipaphis erysimi

Imidacloprid application, as a seed coating agent on oilseed rape, is recommended to control mustard aphid, Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae). In this study, responses of L. erysimi were investigated, including survival, feeding behavior, and detoxifying enzymes, on the oilseed rape seedlings grown from seeds coated with imidacloprid at rates of 6, 12, or 18 g active ingredient (a.i.)/kg seed. The results showed that the aphids’ survival rate, together with that of the progeny of the survivors, on the seed-treated seedlings significantly decreased. This indicates that the aphid population in fields can be suppressed effectively. The electrical penetration graph (EPG) technique was used to record aphid feeding behaviors on two-, four-, and six-leaf stages of oilseed rape seedlings that had been seed-coated with imidacloprid, and individual responses were revealed during the aphid feeding behavior. On the plants at the two-leaf stage, aphid feeding behaviors were influenced, showing decreased frequency of stylet penetration into the leaf (probe) or into the mesophyll cells (potential drops, pds for short), and shortened duration of stylet event in the leaf (probe) or in the phloem. On the plants at the four- and six-leaf stages, these impacts of imidacloprid were weakened; however, the saliva secretion duration in phloem was shortened to less than 5 min in all imidacloprid treatments. The activity of mixed-function oxidase in aphids maintained on the treated seedlings with imidacloprid was elevated. In conclusion, imidacloprid could be used as a seed coating agent for aphid control, but chemical resistance in aphids should not be ignored.